Numerical study on aerothermal performance of shroud movement in the vivinity of turbine tips

In this paper, the effects of shroud movement on transonic flow and heat transfer in the vicinity of turbine tip was studied by using 3-D simulation of GE-E3 first-stage high pressure turbine. Aerothermal performance and flow structure were analyzed with and without turbine shroud moving, respectively. Based on the distribution of limiting streamlines and the vortex structures, the influential characteristics between the leakage flow and the secondary flow generated by shroud movement were studied. Moreover, the coefficient of heat transfer at the wall was investigated. Results show that the flow structure is changing with the movement of turbine shroud, and the location of the separation-line changes significantly by the influence of the secondary flow. The leakage vortex initial location delayed in axial direction and its breakdown point located at 65% cross-section. This accelerates the mixing loss and increase the perturbation. In addition, it is observed that the coefficient of average heat transfer is increased obviously by 54.8% in the region of shroud surface. However, this coefficient in the region of suction surface decreased by 11.9%.